JB from 4.0.1 -> 4.1 keeping 1.59BB?

So a friend has asked me to JB his phone for him. He's never updated his phone since getting it so he still has a stock 4.0.1 on it with 1.59BB. He wants to go to 4.1 only (he really wants GameCenter for some reason) while maintaining his BB for unlocking purposes.

Now, I just needed to see if I had the process for this correct prior to doing anything. If something is incorrect, let me know.

Initially, I'll use TU to grab his SHSH's.While leaving TU on in the background, I'll put the phone into DFU mode and then Option+Restore (I have a Mac) and select the 4.1 IPSW I have as the new OS. I've never done this before as I've only downgraded in the past so this process is a bit new to me.

I'm under the assumption that leaving TU running will keep the BB intact while still updating to 4.1 and then hit the Kick Me Out of Recovery to finish the process.

My other option was simply to use jailbreakme.com, let Cydia make my life easier and install ultrasn0w. Then do the updating process using TU running in the background but this process seems longer I think.

@OP: In a similar situation as you and will be following this tutorial to walk me through the process. GL!

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Just a follow-up: I am now running 4.1 with bb 1.59 and JB'd through Limera1n. Had a bit of a scare through the process but I'm happy to report that all is well . Couple of things I'd like to point out from that guide:

You have to click ALT/OPTION + RESTORE (not SHIFT) to select the 4.1 firmware that you downloaded separately

As soon as you receive error 1004, click on "Exit Recovery" in TinyUmbrella - do not click "OK" or anything in that iTunes dialog box. Doing so will prevent the phone from exiting Recovery Mode.

After completion of the guide linked above, you then have to JB using your software of choice (I followed the guide on iClarified for Limera1n on the Mac, worked like a charm)

I'm under the assumption that leaving TU running will keep the BB intact while still updating to 4.1 and then hit the Kick Me Out of Recovery to finish the process.

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You aren't just keeping the program open, you are also starting the TSS server which is a button you must click. This is crucial to preserving the baseband, along with having TU edit your hosts file for you automatically so it's not pointing at Apple.

My other option was simply to use jailbreakme.com, let Cydia make my life easier and install ultrasn0w. Then do the updating process using TU running in the background but this process seems longer I think.

Click to expand...

Actually you'd update with Tiny Umbrella's TSS server running first to get to 4.1, then you'd use jailbreakme.com after you were already activated, then install ultrasn0w.

For everyone else out there the OP stated he had 1.59.00 BB. This will only be found on the iphone 4 and not any other generation of the iphone.

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